It’s universally acknowledged that anyone sitting next to a person who is using a device — phone, laptop, whatever — is allowed to spy. If you’re tapping away on something, expect to have your emails and texts peered at by your seatmates. That’s the price we all pay for having private conversations on a public platform. But it’s also a rule that you’re not supposed to make the spying obvious. You’re not supposed to lean over, point to the other person’s screen, and say, “Why don’t you count to 10 before you send that text?” or “I think you misspelled chlamydia.” 

Last week, I was waiting for the ferry from Hyannis to Nantucket and had ducked into the waiting area to do a little work before they started loading up the cars. The fellow sitting next to me didn’t know this rule, apparently, because he leaned over to helpfully suggest “You need to get a new computer.” He had noticed the deep cracks in the lower edge of my laptop screen. And he kept at it. “Looks like you dropped it?” asked my new friend. “Or maybe did you close it on something?”